LINKAGE OF 17-BETA-ESTRADIOL DEHYDROGENASE TO ACTIN BY EPSILON-(GAMMA-GLUTAMYL)-LYSINE IN PORCINE ENDOMETRIAL CELLS

We report on the discovery of interactions of porcine endometrial 17be ta-oestradiol dehydrogenase with actin. The 17beta-oestradiol dehydrog enase of porcine uteri is an essentially unidirectional enzyme compoun ded in specialized organelles. The enzyme activity in Brij 35 extracts of the particulate fraction of epithelial cells sedimenting between 1 800 and 11 000 g(av). was collected by immunoadsorption and eluted at low pH. The eluate contained three proteins of 32, 45 and 80 kDa as sh own by SDS/PAGE and silver staining. They were identified by amino aci d sequencing and immunotyping as oestradiol dehydrogenase (32 kDa), ac tin (45 kDa) and a covalent dehydrogenase-actin complex (80 kDa). Disu lphides, aldimines, periodate-degradable bonds and hydrophobic interac tions were excluded as linkages in the 80 kDa protein. The epsilon-(ga mma-glutamyl)-lysine nature of the covalent crosslink was recognized b y narrow-bore h.p.l.c. analysis of enzymic digests of electroeluted 80 kDa material. An involvement of the actin anchor in positioning of th e oestradiol dehydrogenase-containing organelles according to metaboli c requirements is discussed.